autoanticorpos

Autoantibodies, or autoanticorpos in Portuguese, are immunoglobulins produced by B cells that recognize self-antigens—proteins or cell components of the body. In health, central and peripheral tolerance limit self-reactivity, but these mechanisms can fail in susceptible individuals, leading to autoantibody production. Autoantibodies can be organ-specific, targeting a particular tissue (such as thyroid peroxidase in autoimmune thyroiditis), or systemic, reacting with multiple antigens or circulating in immune complexes (as in systemic lupus erythematosus).

Common examples include anti-dsDNA and anti-Smith antibodies in lupus, anti-RNP/ENA in mixed connective tissue disease, anti-thyroid antibodies (TPO, thyroglobulin) in autoimmune thyroid disease, anti-GAD65 and IA-2 in type 1 diabetes, and anti-AChR or anti-MuSK antibodies in myasthenia gravis. Rheumatoid factor and anti-CCP antibodies are associated with rheumatoid arthritis.

In disease, autoantibodies contribute to pathology through mechanisms such as immune complex deposition, complement activation, or blockade or stimulation of receptor function. Not all autoantibodies are pathogenic; some reflect immune dysregulation without causing tissue injury, and a minority can be present in healthy individuals, particularly ANA at low titer.

Diagnosis typically involves serologic testing guided by clinical features. Antinuclear antibodies (ANA) are common screening marks, followed by disease-specific panels. The presence and level of certain autoantibodies can aid diagnosis, prognosis, and monitoring, but interpretation requires clinical context. Treatments target the underlying autoimmune process, including immunosuppressive medications, B cell–depleting therapies, plasmapheresis, or intravenous immunoglobulin in selected cases.